The objective of this project is to develop the technology and biological insight with which to accurately assess the functional competence of individual human spermatozoa. Using videomicrography, we will classify the morphology of living spermatozoa and make simultaneous measurements of their physiology. Sperm motiliy will be analyzed in semen, in cervical mucus and following capacitation in vitro. The penetration of spermatozoa into human cervical mucus and their interaction with the human zona pellucida and zona-free hamster eggs will be measured. Spermatozoa from men with proven fertility and infertility will be studied. We will study the structural and physiological alterations in spermatozoa which coincide with loss of fertility in the vas deferens (after vasectomy) and in the female cervix (after artificial insemination) to gain insight into which parameters identify individual spermatozoa as being senescent and thus potentially infertile. A new competitive gamete interaction assay will be used to study the in vitro fertilizing capacity of sperm from the semen donors in a therapeutic artificial insemination program. The results of this and the other tests of sperm morphology and physiology will be compared with the relative fertility of the donors. These experiments will provide new information on which morphological and physiological parameters can best be used to identify a human spermatozoon as fertile or non-fertile. This will lead to more sensitive methods for diagnosing male infertility and for monitoring the results of therapy.